1. Field of the Invention
The invention relates to a construction apparatus designed with an extendable mast having an upper mast element and a lower mast element, whereby the upper mast element is longitudinally displaceable relative to the lower mast element, a linear drive for displacement of the two mast elements relative to each other, wherein the linear drive has an upper drive part which can be actuated in a linear manner relative to a lower drive part of the linear drive, and a locking device for locking the two mast elements in an extended mast position.
The invention further relates to a method for operating a construction apparatus, in particular a construction apparatus according to the invention, in which the linear drive is extended and in doing so the upper mast element is extended, afterwards the two mast elements are locked in an extended mast position, afterwards the lower drive part is released from the lower mast element and the lower drive part is moved longitudinally of the lower mast element and in doing so a workload arranged on the lower drive part is lifted.
2. Description of Related Art Including Information Disclosed Under 37 CFR §§1.97 and 1.98
A generic construction apparatus is known from JP 2002-285775. This printed publication discloses a construction apparatus with a two-part extendable mast. For the extension of the mast a mast cylinder is provided. This mast cylinder is connected on its piston rod to the lower mast element. On its cylinder housing the mast cylinder has a contact-pressure surface that takes along the upper mast element during the extension of the mast cylinder. In addition to the mast cylinder also a feed cylinder for displacement of a drilling carriage is present.
In accordance with JP 2002-285775 the cylinder housing of the feed cylinder is connected to the cylinder housing of the mast cylinder. Due to this connection the drilling carriage also has to be lifted during the extension of the upper mast element so that correspondingly high power needs to be applied for the extension.